1. Field of the Invention
The present invention relates to a film-forming apparatus and a film-forming method which form a color filter, orientation film, or another such specific film with substantially a uniform thickness on a substrate.
2. Background Information
When a substrate is to be coated with a material (film-forming material) for forming a color filter or an orientation film or other film, the substrate surface is generally subjected to a certain treatment (surface-improving treatment such as lyophilic treatment) in order to improve the wet-spreading (wettability, lyophilicity) of the film-forming material on the surface of the substrate. Such treatment improves the wettability of the substrate and makes it possible, for example, for an orientation film for a liquid crystal display device to be stably formed with a uniform thickness on the substrate.
It is known that when the substrate surface is subjected to a specific treatment such as the one described above to improve the wettability of the substrate, the substrate has sufficient wettability immediately after the treatment is performed. However, the wettability deteriorates over time. If, for example, an accident occurs in the production line, it may take longer time than it would ordinarily for the substrate that has been subjected to the treatment to be conveyed to the apparatus where the film-forming material is applied.
When it takes longer time for the substrate to be conveyed than is ordinarily required, the substrate may be coated with a film-forming material without sufficient wettability on the surface of the substrate. In such cases, for example, display defects in the liquid crystal display device may result. However, there has been no control over the time it takes for the substrate that has been subjected to the treatment to reach the apparatus where the film-forming material is applied. Accordingly, it has been impossible to determine whether the substrate has sufficient wettability.
Inkjet droplet ejection apparatuses are often used to form an orientation film or another film to curtail the consumption of film-forming material and to reduce the number of manufacturing steps in the film-forming process. When a film is formed using an inkjet droplet ejection apparatus, the wettability of the substrate has a greater effect on the thickness of the resulting film than when the film is formed by dispensing or spin coating, for example. Specifically, if the substrate does not have sufficient wettability, it is difficult to form a uniform film.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for improved film forming apparatus and film forming method that overcome the problem of the conventional art. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.